Add dmcache input plugin (#1667)

plugins/inputs/dmcache/dmcache_linux.go

@@ -0,0 +1,190 @@
+// +build linux
+
+package dmcache
+
+import (
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"errors"
+
+	"github.com/influxdata/telegraf"
+)
+
+const metricName = "dmcache"
+
+type cacheStatus struct {
+	device            string
+	length            int
+	target            string
+	metadataBlocksize int
+	metadataUsed      int
+	metadataTotal     int
+	cacheBlocksize    int
+	cacheUsed         int
+	cacheTotal        int
+	readHits          int
+	readMisses        int
+	writeHits         int
+	writeMisses       int
+	demotions         int
+	promotions        int
+	dirty             int
+}
+
+func (c *DMCache) Gather(acc telegraf.Accumulator) error {
+	outputLines, err := c.getCurrentStatus()
+	if err != nil {
+		return err
+	}
+
+	totalStatus := cacheStatus{}
+
+	for _, s := range outputLines {
+		status, err := parseDMSetupStatus(s)
+		if err != nil {
+			return err
+		}
+
+		if c.PerDevice {
+			tags := map[string]string{"device": status.device}
+			acc.AddFields(metricName, toFields(status), tags)
+		}
+		aggregateStats(&totalStatus, status)
+	}
+
+	acc.AddFields(metricName, toFields(totalStatus), map[string]string{"device": "all"})
+
+	return nil
+}
+
+func parseDMSetupStatus(line string) (cacheStatus, error) {
+	var err error
+	parseError := errors.New("Output from dmsetup could not be parsed")
+	status := cacheStatus{}
+	values := strings.Fields(line)
+	if len(values) < 15 {
+		return cacheStatus{}, parseError
+	}
+
+	status.device = strings.TrimRight(values[0], ":")
+	status.length, err = strconv.Atoi(values[2])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.target = values[3]
+	status.metadataBlocksize, err = strconv.Atoi(values[4])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	metadata := strings.Split(values[5], "/")
+	if len(metadata) != 2 {
+		return cacheStatus{}, parseError
+	}
+	status.metadataUsed, err = strconv.Atoi(metadata[0])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.metadataTotal, err = strconv.Atoi(metadata[1])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.cacheBlocksize, err = strconv.Atoi(values[6])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	cache := strings.Split(values[7], "/")
+	if len(cache) != 2 {
+		return cacheStatus{}, parseError
+	}
+	status.cacheUsed, err = strconv.Atoi(cache[0])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.cacheTotal, err = strconv.Atoi(cache[1])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.readHits, err = strconv.Atoi(values[8])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.readMisses, err = strconv.Atoi(values[9])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.writeHits, err = strconv.Atoi(values[10])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.writeMisses, err = strconv.Atoi(values[11])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.demotions, err = strconv.Atoi(values[12])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.promotions, err = strconv.Atoi(values[13])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+	status.dirty, err = strconv.Atoi(values[14])
+	if err != nil {
+		return cacheStatus{}, err
+	}
+
+	return status, nil
+}
+
+func aggregateStats(totalStatus *cacheStatus, status cacheStatus) {
+	totalStatus.length += status.length
+	totalStatus.metadataBlocksize += status.metadataBlocksize
+	totalStatus.metadataUsed += status.metadataUsed
+	totalStatus.metadataTotal += status.metadataTotal
+	totalStatus.cacheBlocksize += status.cacheBlocksize
+	totalStatus.cacheUsed += status.cacheUsed
+	totalStatus.cacheTotal += status.cacheTotal
+	totalStatus.readHits += status.readHits
+	totalStatus.readMisses += status.readMisses
+	totalStatus.writeHits += status.writeHits
+	totalStatus.writeMisses += status.writeMisses
+	totalStatus.demotions += status.demotions
+	totalStatus.promotions += status.promotions
+	totalStatus.dirty += status.dirty
+}
+
+func toFields(status cacheStatus) map[string]interface{} {
+	fields := make(map[string]interface{})
+	fields["length"] = status.length
+	fields["metadata_blocksize"] = status.metadataBlocksize
+	fields["metadata_used"] = status.metadataUsed
+	fields["metadata_total"] = status.metadataTotal
+	fields["cache_blocksize"] = status.cacheBlocksize
+	fields["cache_used"] = status.cacheUsed
+	fields["cache_total"] = status.cacheTotal
+	fields["read_hits"] = status.readHits
+	fields["read_misses"] = status.readMisses
+	fields["write_hits"] = status.writeHits
+	fields["write_misses"] = status.writeMisses
+	fields["demotions"] = status.demotions
+	fields["promotions"] = status.promotions
+	fields["dirty"] = status.dirty
+	return fields
+}
+
+func dmSetupStatus() ([]string, error) {
+	out, err := exec.Command("/bin/sh", "-c", "sudo /sbin/dmsetup status --target cache").Output()
+	if err != nil {
+		return nil, err
+	}
+	if string(out) == "No devices found\n" {
+		return []string{}, nil
+	}
+
+	outString := strings.TrimRight(string(out), "\n")
+	status := strings.Split(outString, "\n")
+
+	return status, nil
+}